Thermosetting resin composition, and prepreg, laminate for circuit board, and printed circuit board each made therewith

ABSTRACT

The present invention discloses a thermosetting resin composition which comprises (A) 35 to 75 parts by weight of a thermosetting resin comprising a compound having a dihydrobenzoxazine ring as a main component, (B) 10 to 25 parts by weight of a polycondensation product of a phenol, a compound having a triazine ring and an aldehyde, and (C) 10 to 45 parts by weight of an epoxy resin, based on 100 parts by weight of the total amount of organic solid components of Components (A), (B) and (C), and (i) a bisphenol F epoxy resin having a weight average molecular weight of 1,000 to 3,000, or (ii) a mixed epoxy resin of bisphenol F epoxy resin and bisphenol A epoxy resin having a weight average molecular weight of 1,000 to 3,000, is contained in Component (C) in an amount of 0 to 100% by weight of Component (C); and a prepreg, a laminated board for a wiring board and a wiring board using the same.

TECHNICAL FIELD

[0001] The present invention relates to a thermosetting resincomposition and its uses such as a prepreg, a laminated board for aprinted wiring board, a printed wiring board, a molding material and acomposition for adhesive, and particularly, to a thermosetting resincomposition suitable for a high-frequency circuit board of the MHz bandor higher that takes advantage of low dielectric dissipation factor, andfor impregnation of a glass substrate for a built-up type base boardthat takes advantage of high modulus of elasticity.

BACKGROUND ART

[0002] In recent years, electronic equipments have generally beenrequired to offer lighter weight and more compact size. In accommodationof this, although the printed wiring boards used inside these equipmentspredominantly consist of 4-10 layers, in order to accommodatehigh-density mounting, efforts are being made to increase patternfineness, and further to reduce mounting height and employ a built-upconstitution.

[0003] Printed wiring boards are required to have low dielectricdissipation factor as well as be stable over a wide temperature rangeand wide frequency band in order to inhibit transmission loss when usedin high-frequency circuits and ensure stable operation of the circuit intheir temperature range and frequency bands. In addition, sincematerials having large dimensional expansion and contraction rates arefrequently used for the surface built-up layer in built-up boardsenabling low mounting height and high density mounting, they aresusceptible to the occurrence of considerable warping due to contractionduring curing and cooling of the surface built-up layer. Consequently,the printed wiring boards and multi-layer wiring boards on both sides ofthe inside core layer are required to be thin and have high rigidity. Inaddition, accompanying the use of a lead-free material for a solder, themelting point of the solder is expected to be higher, thereby resultingin the need for higher moisture absorption-heat resistance andreliability.

[0004] Thus, the materials for printed wiring boards are required toadequately possess all of the characteristics of low dielectricdissipation factor, high modulus of elasticity, high heat resistance,low moisture absorption and high glass transition point (Tg).

[0005] In addition, these materials are also required to be flameretardant in consideration of safety. Consequently, attempts have beenmade to ensure flame retardancy by combining the use of halogen-basedflame retardants, antimony compounds or phosphorous-based flameretardants. In recent years, however, there has been a growing trendtowards controls on substances used in consideration of environmentalpollution and toxicity, and the toxicity and carcinogenicity of organichalogen substances such as dioxin in particular have become a problem.Consequently, there is a strong need to reduce or eliminatehalogen-containing substances, and according to JPCA standards,halogen-free materials are defined as having individual contents ofhalogen elements being 0.09% by weight or less. In order to satisfy thisstandard value, it is necessary to suppress the content of each halogenelement in the resin used to 0.25% by weight or less even in the case inwhich the halogen content in the resin is at the highest allowed levelfor the lowest amount of the resin used and the minimum resin weightbeing about 38% of the total weight of the prepreg.

[0006] In order to satisfy the above requirements, materials in which anepoxy resin, a polyimide resin or an isocyanate resin is improved ormodified have been researched. Among these, resins having adihydrobenzoxazine ring have superior characteristics such as lowdielectric dissipation factor, high modulus of elasticity, high heatresistance, low moisture absorption, high Tg and high flame retardancy,so that they have been attempted to use in a substrate for wiring boardsand so forth. However, since resins having a benzoxazine ring have arigid skeleton, they do not exhibit toughness. Consequently, they aresusceptible to the occurrence of inner layer separation during blank dieprocessing, and have poor discharge of cuttings during small diameterdrilling, resulting in the problem of susceptibility to occurrence ofbreakage of the drill bit. In order to solve such problems, it isnecessary to blend epoxy resin into the resin composition at 40 parts byweight or more based on 100 parts by weight of the organic solidcomponents as disclosed in Japanese Patent Laid-Open Publication No.11-158352. However, when such epoxy resin is formulated in relativelylarge amounts, problems occur including loss of the inherentcharacteristics of low dielectric dissipation factor, high modulus ofelasticity, high heat resistance, low moisture absorption, high Tg andsuperior processability, while also preventing the attainment of V-0flame retardancy as specified in standard UL94 pertaining to flameretardancy in thin materials.

[0007] Consequently, a printed wiring board material is required thathas low dielectric dissipation factor, high modulus of elasticity, highheat resistance, low moisture absorption, high Tg as well as a halogenand antimony compound content in a thermosetting resin composition of0.25% by weight or less, and flame retardancy of V-0 in standard UL94.

SUMMARY OF THE INVENTION

[0008] An object of the present invention is to solve theabove-mentioned problems and to provide a thermosetting resincomposition in which the halogen and antimony compound content is 0.25%by weight or less and which has a proper balance between processabilityand characteristics such as low dissipation factor, high modulus ofelasticity, high heat resistance, low moisture absorption, high Tg andflame retardancy, along with a prepreg, laminated board for a wiringboard, printed wiring board, molding material and adhesive compositionin which it is used.

[0009] The present invention relates to a thermosetting resincomposition which comprises:

[0010] (A) 35 to 75 parts by weight of a thermosetting resin comprisinga compound having a dihydrobenzoxazine ring as a main component;

[0011] (B) 10 to 25 parts by weight of a polycondensation product of aphenol, a compound having a triazine ring and an aldehyde; and

[0012] (C) 10 to 45 parts by weight of an epoxy resin, based on 100parts by weight of the total amount of the organic solid components ofComponents (A), (B) and (C); and

[0013] (i) a bisphenol F type epoxy resin having a weight averagemolecular weight of 1,000 to 3,000, or

[0014] (ii) a mixed epoxy resin of bisphenol F type epoxy resin andbisphenol A type epoxy resin having a weight average molecular weight of1,000 to 3,000, is contained in Component (C) in an amount of 4 to 100%by weight of Component (C).

BEST MODE FOR CARRYING OUT THE INVENTION

[0015] Component (A) of the present invention is not specificallylimited, namely a thermosetting resin having for its main component acompound having a dihydrobenzoxazine ring, provided it is a resin thatis cured by a ring-opening reaction of the dihydrobenzoxazine ring. Inconsideration of both of characteristics such as low dielectricdissipation factor, high modulus of elasticity, high heat resistance,low moisture absorption, high Tg and high flame retardancy, and dieprocessability, Component (A) is contained in the composition of thepresent invention in an amount of 35 to 75 parts by weight, preferably40 to 70 parts by weight based on 100 parts by weight of the totalamount of the organic solid components of Components (A), (B) and (C).

[0016] Moreover, making the softening point of the thermo-setting resincomprising a compound having a dihydrobenzoxazine ring as a maincomponent 11° C. or lower decreases the shortcoming of the skeletonbeing rigid and lacking toughness, and is effective in reducing innerlayer separation during blank die punching as well as improving peelstrength of the inner layer that exhibits adhesive strength with theresin layer in contact with the inner layer circuit of multi-layerwiring boards.

[0017] According to the present invention, Component (A) can be producedfrom a compound having a phenolic hydroxyl group, a primary amine andformaldehyde as represented by the following formula:

[0018] wherein R¹ represents an alkyl group, a cycloalkyl group such asa cyclohexyl group, etc., or an aromatic group such as a phenyl group ora phenyl group which may be substituted by an alkyl group or an alkoxygroup.

[0019] As the above-mentioned compound having a phenolic hydroxyl group,there may be mentioned polyfunctional phenols, biphenol compounds,bisphenol compounds, trisphenol compounds, tetraphenol compounds andphenol resins. Examples of the polyfunctional phenols include catechol,hydroquinone and resorcinol. Examples of the bisphenol compounds includebisphenol A, bisphenol F and its positional isomers, bisphenol S andtetrafluorobisphenol A. In addition, examples of the phenol resins mayinclude resol resin, phenol novolak resin, phenol-modified xylene resin,alkylphenol resin, melamine phenol resin, benzo-guanamine phenol resinand phenol-modified polybutadiene.

[0020] In addition, formaldehyde can be used in the form of formalin,paraformaldehyde and so on. Moreover, examples of the primary amines mayinclude methylamine, cyclohexylamine, aniline and substituted aniline.

[0021] According to the present invention, it can be synthesized byadding a mixture of a compound having a phenolic hydroxyl group and aprimary amine to formaldehyde heated to 70° C. or higher, reaching at 70to 11° C., preferably at 90 to 100° C. for 20 to 120 minutes, and thendrying under reduced pressure at a temperature of 120° C. or lower.

[0022] Examples of phenols used to obtain Component (B) of the presentinvention, namely the polycondensation product of a phenol, a compoundhaving a triazine ring and an aldehyde, may include phenol, polyvalentphenols such as bisphenol A, bisphenol F or bisphenol S, alkylphenolssuch as cresol, xylenol, ethylphenol or butylphenol, aminophenols andphenylphenols, and one kind or two or more kinds can be used incombination. In the case of using a combination of phenol and bisphenolA or a combination of phenol and alkylphenol, it is preferable due tosuperior moldability resulting from reactivity being inhibited to agreater extent than in the case of using phenol alone, and is alsopreferable due to superior flame retardancy as compared with usingbisphenol A or alkylphenol alone.

[0023] In addition, examples of the compounds having a triazine ring mayinclude melamine or guanamine derivatives such as benzoguanamine andacetoguanamine, cyanuric acid or cyanuric acid derivatives such asmethylcyanurate and ethylcyanurate, and isocyanuric acid or isocyanuricacid derivatives such as methylisocyanurate and ethylisocyanurate.Melamine is suitable due to its satisfactory heat resistance and flameretardancy as well as its low price, and the type and amount used of thecompound having a triazine ring can be selected according to thepurpose, and flame retardancy, reactivity and heat resistance can beoptimized by adjusting the N content.

[0024] Examples of the aldehydes may include formaldehyde,paraformaldehyde, trioxane and tetraoxymethylene. Although the aldehydeis not limited to these, in terms of ease of handling, formaldehyde ispreferable, and formalin or paraformaldehyde is particularly preferable.

[0025] The synthesis method of the modified phenol resin used in thepresent invention comprises reacting the major materials of the abovephenols, compound having a triazine ring and aldehydes in the presenceof a catalyst by blending at a desired N (nitrogen) content and ahydroxyl group equivalent. As the catalyst at this time, basic catalystsare preferable due to the satisfactory solubility of the compound havinga triazine ring. In particular, amines are preferable since metals andso forth are not preferable as electrical insulating materials if theyremain in the form of catalyst residue. The order of the reaction is notspecifically limited, and all major materials can be reactedsimultaneously or two types of major materials can be reactedselectively in advance. Reaction is preferably carried out in thepresence of various kinds of solvents such as acetone and methyl ethylketone since it enables stable control of the reaction. The modifiedphenol resin used in the present invention can be obtained by removingunreacted phenols, aldehydes and solvent by neutralization, washing,heat treatment or distillation, etc. the reaction product in accordancewith the conventional manner.

[0026] In the above reaction, a molar ratio of the aldehyde to thephenol is not particularly limited, and it is preferably 0.2 to 1.5,more preferably 0.4 to 0.8. In addition, a weight ratio of the compoundhaving a triazine ring to the phenol is preferably 10 to 98:90 to 2, andmore preferably 50 to 95:50 to 5, in consideration of both ofresinification and flame retardant effects.

[0027] Moreover, by combining several kinds of the modified phenolresins of the present invention or by using as a curing agent incombination with novolak resins as other phenols, moldability, flameretardancy and heat resistance can be obtained that cannot be obtainedwhen using the modified phenol resin alone, and using in combinationaccording to the purpose is also preferable.

[0028] In addition, in consideration of the ratio and heat curingreactivity in the reaction of individual components, Component (B) iscontained in the composition of the present invention in an amount of 10to 25 parts by weight, preferably 15 to 20 parts by weight based on 100parts by weight of the total amount of the organic solid components ofComponents (A), (B) and (C).

[0029] Examples of the epoxy resin of Component (C) of the presentinvention may include bisphenol A type epoxy resin, bisphenol F typeepoxy resin, phenol novolak type epoxy resin, bisphenol A novolak typeepoxy resin, cresol novolak type epoxy resin, cyclic aliphatic epoxycompounds, heterocyclic epoxy compounds and diglycidyl ester type epoxycompounds, although not particularly limited to these. These may be usedalone or in combination of two or more kinds.

[0030] Moreover, according to one embodiment of the present invention,in the case of not containing (i) bisphenol F type epoxy resin or (ii)an epoxy resin that is a mixture of bisphenol F type epoxy resin andbisphenol A type epoxy resin (hereinafter abbreviated to as a mixedepoxy resin) in the composition of the present invention, inconsideration of both of punching processability and dielectricdissipation factor (as well as modulus of elasticity, flame retardancyand Tg), Component (C) is contained in the composition of the presentinvention in an amount of 10 to 40 parts by weight, preferably 15 to 40parts by weight based on 100 parts by weight of the total amount of theorganic solid components of Components (A), (B) and (C).

[0031] According to another embodiment of the present invention, (i)bisphenol F type epoxy resin or (ii) the mixed epoxy resin is containedin Component (C) as a part or all of the same. Here, Components (i) and(ii) have a weight average molecular weight (Mw) of 1,000 to 3,000,preferably 1,500 to 2,500. Examples of Components (i) and (ii) mayinclude R-304PD or R-364 available from Mitsui Chemical Co., Ltd.Component (i) or (ii) is contained in Component (C) in an amount of 0 to100% by weight, preferably 4 to 60% by weight, of Component (C). Inother words, a part or all of Component (C) uses Component (i) or (ii)in an amount of 2 to 30 parts by weight, preferably 2 to 25 parts byweight based on 100 parts by weight of the total amount of the organicsolid components of Components (A), (B) and (C) (here, the amount ofbisphenol F type epoxy resin or the mixed epoxy resin does not exceedthe amount of Component (C) as a matter of course). Incidentally, in thecase of using Component (i) or (ii) for a part or all of Component (C),Component (C) is used in an amount of 10 to 45 parts by weight,preferably 30 to 45 parts by weight based on 100 parts by weight of thetotal amount of the organic solid components of Components (A), (B) and(C). Since Component (i) or (ii) has superior flame retardancy incomparison with the bisphenol A type epoxy resin, it can be added in theabove amount without impairing the object of the present invention.

[0032] An inorganic filler as Component (D) can also be contained in thecomposition of the present invention. As Component (D), the inorganicfiller, known materials can be used without any specific limitation, andcan be selected according to the purpose of use. Examples thereof mayinclude inorganic hydrates such as aluminum hydroxide, magnesiumhydroxide, zeolite and hydrotalcite; typically used inorganic fillerssuch as clay, talc, wallastonite, mica, calcium carbonate, magnesiumcarbonate, alumina, silica and glass powder; B- or Sn-based fillers suchas zinc borate, zinc stannate and zinc hydroxystannate; metal oxidessuch as zinc oxide and tin oxide; inorganic phosphorous materials suchas red phosphorous; and nitrates such as those of copper and zinc. Inaddition, the inorganic filler is preferably coated or surface treatedwith a silane coupling agent, a titanate coupling agent or zincmolybdenate and so forth to improve adhesion with organic components,heat resistance, as well as stability with respect to temperature andhumidity, and safeness.

[0033] Component (D), the inorganic filler is preferably contained in anamount of 5 to 300 parts by weight, more preferably 10 to 260 parts byweight, even more preferably 20 to 250 parts by weight, and particularlypreferably 30 to 100 parts by weight based on 100 parts by weight of thetotal amount of the organic solid components of Components (A), (B) and(C).

[0034] In addition, in order to achieve the target flame retardancy byusing only a halogen-free material, the limit on the content of thetriazine ring in the thermosetting resin composition of the presentinvention, namely the N content that is effective for enhancing flameretardancy, is up to 5% by weight or so in the organic resin solidcomponents, and it is not possible to attain flame retardancy of V-1 orV-0 in the standard UL94 unless either a special epoxy resin is usedwhile ignoring other characteristics and moldability or significantlyincreasing the amount of the phenol resin composition. Consequently, inorder to attain flame retardancy of V-1 or V-0 of the standard UL94, itis necessary to have an additive assistant effect in flame retardancy.In order to achieve this, it is preferable to add 5 parts or more ofinorganic filler to decrease the percentage of flammable substancespresent, and in order to attain flame retardancy of V-0 in the standardUL94, it is preferable to use 30 parts or more of inorganic hydrate forthe inorganic filler. In addition, in the case of not using aphosphor-containing compound for the additive, it is preferable to use100 parts or more thereof to improve tracking resistance. Moreover, theamount of inorganic filler added is preferably 260 parts or less inconsideration of the target values of the resulting epoxy resincomposition such as adhesion with metal foil, heat resistance,processability and insulation, as well as composite molding with anon-woven fabric or woven fabric base material and so forth. (E) acondensed phosphate ester can be blended into the thermosetting resincomposition of the present invention. The condensed phosphate ester hasthe structure represented by, for example, the following formula:

[0035] wherein R², R³ and R⁴ each represent an organic group includingan alkyl group, a cycloalkyl group such as a cyclohexyl group, or anaromatic group such as a phenyl group (including a phenyl group that maybe substituted by an alkyl group or alkoxy group), and each may be thesame or different from each other, m is 1, 2 or 3, and n represents thenumber of the substituent R², R³ or R⁴, and each independentlyrepresents 0, 1 or 2 for R², R³ or R⁴.

[0036] The condensed phosphate esters have effects of overcoming thedefects that high-temperature chemical resistance, humidity and heatresistance and Tg are significantly lowered by condensing a phosphateester to have a high melting point.

[0037] Component (E) improves flame retardancy, and in consideration ofboth its effect of improving flame retardancy as well as humidity andheat resistance and Tg, it is preferably contained in an amount of 5 to35 parts by weight, more preferably 5 to 30 parts by weight, even morepreferably 5 to 20 parts by weight, and particularly preferably 10 to 20parts by weight based on 100 parts by weight of the organic resin solidcomponents of Components (A), (B) and (C).

[0038] The thermosetting resin composition of the present invention mayalso contain (F) epoxidized polybutadiene. (F) the epoxidizedpolybutadiene is preferably contained in an amount of 1 to 20 parts byweight, more preferably 1 to 15 parts by weight, and further preferably1 to 10 parts by weight based on 100 parts by weight of the total amountof the organic solid components of said Components (A), (B) and (C).

[0039] The thermosetting resin composition of the present invention maycontain (G) a copolymerizable component. (G) is a copolymerizablecomponent, and is preferably at least one selected from the groupconsisting of acrylonitrile, acrylic acid, ethyl acrylate, butylacrylate, glycidyl acrylate, butadiene, ethyl methacrylate, butylmethacrylate and styrene. In consideration of the effect of improvingpunchability and inner layer peeling as well as both flame retardancyand Tg, Component (G) is preferably contained in an amount of 1 to 20parts by weight, more preferably 1 to 15 parts by weight, furtherpreferably 1 to 10 parts by weight, and particularly preferably 1 to 5parts by weight based on 100 parts by weight of the total amount of theorganic solid components of said Components (A), (B) and (C). Thispolymer may include those having a core shell structure in which acomponent having a different inside core portion is coated onto thesurface layer portion, and the surface layer may be treated with acoupling agent or that in which a functional group has been introducedmay be used. Component (G) is able to improve punchability and innerlayer peeling.

[0040] In addition to these components, colorant, anti-oxidant, reducingagent, ultraviolet blocker and so forth may also be formulated asnecessary.

[0041] The composition of the present invention is preferably used as avarnish in which the components have been dissolved or dispersed in anorganic solvent. The organic solvent is not specifically limited, and aketone type, an aromatic hydrocarbon type, an ester type, an amide typeor an alcohol type organic solvent can be used. More specifically,examples of the ketone type solvents include acetone, methyl ethylketone, methyl isobutyl ketone and cyclohexanone, examples of thearomatic hydrocarbon type solvents include toluene and xylene, examplesof the ester type solvents include methyoxyethyl acetate, ethoxyethylacetate, butoxyethyl acetate and ethyl acetate, examples of the amidetype solvents include N-methylpyrrolidone, formamide, N-methylformamideand N,N-dimethylacetamide, and examples of the alcohol type solventsinclude methanol, ethanol, ethylene glycol, ethylene glycol monomethylether, ethylene glycol monoethyl ether, diethylene glycol, triethyleneglycol monomethyl ether, triethylene glycol monoethyl ether, triethyleneglycol, propylene glycol monomethyl ether, dipropylene glycol monomethylether, propylene glycol monopropyl ether and dipropylene glycolmonopropyl ether. These solvents may be used singly or in combination oftwo or more kinds as a mixture.

[0042] As the base material of woven fabric or non-woven fabric used inthe prepreg of the present invention, there may be used natural fiberbase materials such as paper or cotton linter; organic synthetic fiberbase materials such as Aramid, polyvinyl alcohol, polyester or acrylicfiber, and inorganic fiber base materials such as glass and asbestos. Aglass fiber base material is preferable from the viewpoint of flameresistance. Examples of the glass fiber base materials may include wovenfabric using E glass, C glass, D glass or S glass, glass non-wovenfabric in which short fibers are adhered with an organic binder, andfurther those in which glass fiber and cellulose fiber are mixed andmade fabric.

[0043] According to the present invention, a prepreg can be produced byimpregnating the above varnish into a base material such as a wovenfabric or non-woven fabric followed by drying. The resulting prepreg maybe laminated with a plurality of layers as necessary, and aftercomposing a metal foil such as copper foil or aluminum foil on bothsurfaces, is subjected to pressurization and hot pressing to obtain ametal clad laminated board.

[0044] According to the present invention, a printed wiring board can beobtained by performing circuit processing on the metal foil of the metalfoil clad laminated board. Circuit processing can be performed by, forexample, forming a resist pattern on the surface of the metal foil,removing unnecessary portions of the foil by etching, removing theresist pattern, forming the required through holes by drilling, againforming the resist pattern, plating to connect the through holes, andfinally removing the resist pattern. A multi-layer printed wiring boardcan be obtained by additionally laminating the above metal foil cladlaminated board on the surface of the printed wiring board obtained inthe above manner under the same conditions as described above, followedby performing circuit processing in the same manner as described above.In this case, it is not always necessary to form through holes, and viaholes may be formed in their place, or both may be formed. Theselaminated boards are then laminated the required number of times.

[0045] The printed wiring board produced in the above manner can belaminated with metal foil provided with adhesive on one surface or bothsurfaces in the form of an inner layer circuit board. This laminationmolding is normally performed under heating and pressurization. Examplesof metal foil include copper foil and aluminum foil. A multilayerprinted circuit board can then be obtained by performing circuitprocessing in the same manner as described above on the resulting metalfoil clad laminated board. The thermosetting resin composition of thepresent invention along with the printed circuit board material in whichit is used are particularly useful in uses of highfrequency circuitboards of the MHz band or greater that take advantage of the lowdielectric dissipation factor, or base boards for built-up that takeadvantage of the high modulus of elasticity.

EXAMPLE

[0046] In the following, the present invention is explained in detail byreferring to Examples, but the present invention is not limited to theseExamples. In the following explanation, part(s) refers to “part(s) byweight” and % refers to “% by weight” otherwise specifically mentioned.

Synthesis Example 1

[0047] (A-1) Synthesis of Thermosetting Resin Comprising aDihydrobenzoxazine Ring as a Main Component

[0048] To a 5 liter volume flask equipped with a thermometer, stirrer,condenser tube and dropping device were added 1000 g of bisphenol F and920 g of methanol, and the mixture was dissolved at 50° C. whilestirring. 652 g of paraformaldehyde were then added to the solution.Moreover, 930 g of aniline were added dropwise over one hour whilestirring, and one hour later, the temperature was raised to 78 to 80° C.After allowing to react for 7 hours while refluxing, the pressure wasreduced and the mixture was concentrated under reduced pressure at apressure of 360 mmHg. Concentration was continued while maintaining thisvacuum degree, and the vacuum degree was increased to 90 mmHg when thetemperature of the resin reached 110° C. After confirming that there wasno more outflow of liquid, the resin was taken out into a vat to producea thermosetting resin (A1) comprising a dihydrobenzoxazine ring as amain component and having a softening point of the resin being 78° C.

Synthesis Example 2

[0049] (A-2) Synthesis of Thermosetting Resin Comprising aDihydrobenzoxazine Ring as a Main Component

[0050] The above thermosetting resin (A1) comprising adihydrobenzoxazine ring as a main component was heated for 6 hours at110° C. under normal pressure to produce a thermosetting resin (A2)comprising a dihydrobenzoxazine ring as a main component and having asoftening point of the resin being 110° C.

Synthesis Example 3

[0051] (A-3 and 4) Synthesis of Thermosetting Resins Comprising aDihydrobenzoxazine Ring as their Main Component

[0052] (1) Synthesis of Phenol Novolak

[0053] Into a 5 liter volume flask were charged 1.9 kg of phenol, 1.15kg of formalin (37% aqueous solution) and 4 g of oxalic acid and themixture was allowed to react for 6 hours at the reflux temperature.Subsequently, the inside of the flask was reduced to a pressure of6666.1 Pa or lower to remove the unreacted phenol and water. Theresulting resin had a softening point of 89° C. (the ring and ballmethod), and the ratio of {(3 core form+3 or more core form)/(2 coreform)} was 89/11 (from peak area ratio as determined by gel permeationchromatography). The core form here refers to the phenol group portion.

[0054] (2) Introduction of Dihydrobenzoxazine Ring

[0055]1.7 kg of the phenol novolak resin synthesized as described above(equivalent to 16 mols of hydroxyl groups) were stirred for 5 hours at80° C. with 1.49 kg (equivalent to 16 mols) of aniline to prepare auniformly mixed solution. 1.62 kg of formalin were charged into a 5liter volume flask and heated to 90° C. Next, the novolak/aniline mixedsolution was then gradually added to the flask over 30 minutes. Twotypes of products were then prepared by holding at the refluxtemperature for 30 minutes following completion of the addition or byholding at the reflux temperature for 90 minutes following completion ofthe addition. Thereafter, the pressure was reduced to 6666.1 Pa or lowerfor 2 hours at 100° C. to remove the condensed water and obtain twotypes of thermosetting resins in which 95% of the hydroxyl groups ableto react were converted to dihydrobenzoxazine. Two types of the resinswere thus obtained consisting of that in which the softening point thatwas held at the reflux temperature for 30 minutes after completion ofthe addition was 70° C. (A3), and that in which the softening point thatwas held to the reflux temperature for 90 minutes after completion ofthe addition was 105° C. (A4).

[0056] (B) Polycondensation product of a phenol, a compound having atriazine ring and an aldehyde

[0057] (B1) LA-7054 (trade name, Dainippon Ink and Chemicals), nitrogencontent: 12%, OH equivalent: 127

[0058] (B2) LA-1356 (trade name, Dainippon Ink and Chemicals), nitrogencontent: 19%, OH equivalent: 146

[0059] (C) Epoxy resin

[0060] (C1) Phenol novolak type epoxy resin

[0061] Epoxy equivalent: 170 to 180 g/eq., liquid at normal temperature

[0062] (C2) Bisphenol F type epoxy resin Mw=2,000, epoxy equivalent: 950to 1050 g/eq., solid at normal temperature

[0063] (C3) Bisphenol F type epoxy resin Mw=340, epoxy equivalent: 160to 180 g/eq., liquid at normal temperature

[0064] (D) Inorganic Filler

[0065] Aluminum hydroxide

[0066] Mean particle diameter: 3 μm to 5 μm, purity: 99% or more

[0067] (E) Condensed phosphate ester

[0068] PX-200 (trade name, Daihachi Chemical)

[0069] (F) Epoxidized butadiene

[0070] PB-3600 (trade name, Daicel Chemical Industries)

[0071] (G) Copolymer

[0072] Butadiene-alkyl methacrylate-styrene copolymer

[0073] EXL-2655, trade name, Kureha Chemical Industry

Examples 1 to 17 and Comparative Examples 1 to 10

[0074] The resin compositions blended with solid components shown inTables 1 to 4 were dissolved in methyl ethyl ketone followed by theaddition of 0.3 part of the amount of the organic solid components of ananti-sedimentation agent of an inorganic filler (trade name: Aerozil200, available from Nippon Aerozil) and 0.3 part of the amount of theorganic solid components of a reducing agent (trade name: Yoshinox BB,available from Yoshitomi Pharmaceutical), and adjusting with methylethyl ketone so that the non-volatile components of the solution were 65to 75% to obtain a varnish. Thereafter, the varnish was impregnated intoa glass cloth (0.2 mm) and dried for 4 minutes at 160° C. to obtain aprepreg.

[0075] Next, 35 μm copper foil was laminated over both surfaces of asingle prepreg, a laminate consisting of four layers of this prepreg, ora laminate consisting of eight layers of this prepreg, followed by hotpress molding for 100 minutes at a temperature of 185° C. and a pressureof 4 MPa to produce both surfaces copper clad laminated boards havingthicknesses of 0.2 mm (single prepreg layer), 0.8 mm (4 prepreg layers)and 1.6 mm (eight prepreg layers), respectively.

[0076] The prepregs prepared above and the both surfaces copper cladlaminated boards prepared above were then arranged in the order of 18 μmcopper foil/prepreg/single prepreg both surfaces copper clad laminatedboard (with copper remaining on all surfaces)/prepreg/18 μm copper foil,while the remainder of the procedure was performed in accordance withestablished methods for producing multi-layer wiring boards to produce afour-layer wiring board.

[0077] Moreover, a resin film with halogen-free copper foil (trade name:MCF-4000G, Hitachi Chemical Industries, Ltd.) was arranged on both sidesof this four-layer wiring board to serve as a built-up layer followed byhot press molding for 100 minutes at a temperature of 185° C. and apressure of 3 MPa to produce a six-layer wiring board having a built-upconstitution.

[0078] The both surfaces copper clad laminated board prepared above(having 8 layers of prepreg) was investigated for dielectric dissipationfactor, modulus of elasticity, amount of peeling during punching, flameretardancy (the both surfaces copper clad laminated board using 8prepreg. layers and the both surfaces copper clad laminated board using4 prepreg layers were used for investigating flame retardancy), humidityand heat resistance, and Tg.

[0079] The results of characteristics relating to dielectric dissipationfactor a, bending modulus of elasticity b, amount of warping ofsix-layer board c, burning resistance (flame retardancy) d, amount ofpeeling during punching e, drill breakage f, peel strength of the innerlayer g, solder heat resistance h and glass transition temperature i areshown in Tables 5 to 8.

[0080] Incidentally, the methods for testing characteristics are asdescribed below.

[0081] (a) Dielectric Dissipation Factor

[0082] Dielectric dissipation factor at 1 GHz was measured in accordancewith IPC TM-650 2.5.5.5 by the resonance method using a strip line.

[0083] (b) Bending Modulus of Elasticity

[0084] Initial modulus of elasticity was measured during the bendingtest of JIS C 6481.

[0085] (c) Amount of Warping of Six-layer Board:

[0086] After removing all of the surface layer copper foil of asix-layer wiring board having a built-up constitution (a board with asize of 250×250 mm) by etching, the board was dried for 30 minutes at150° C. on the assumption of the drying step of solder resist followedby measurement of the amount of warping. Warping is indicated in thetable as the amount of warping of a six-layer board.

[0087] (d) Burning Resistance (Flame Retardancy): in Compliance withUL94.

[0088] (d1) 1.6 mm flame retardancy: Using a both surfaces copper cladlaminated board having 8 prepreg layers

[0089] (d2) 0.8 mm flame retardancy: Using a both surfaces copper cladlaminated board having 4 prepreg layers

[0090] (e) Amount of Peeling During Punching

[0091] The both surfaces copper clad laminated board prepared was usedas the sample after removing the copper foils by etching, and using aDIN mold, the amount of inner layer peeling (mm) during blank dieprocessing was measured to determine the amount of peeling.

[0092] (f) Drill Breakage:

[0093] Four four-layer wiring boards were superimposed on each other and0.25 mm diameter holes were drilled under conditions of a rotating speedof 10 krpm and feeding speed of 2 m/min to test drill breakage up to amaximum of 3,000 holes. A ⊚ indicates no breakage even at 3,000 holes ormore, a ◯ indicates breakage within 3,000 holes, a Δ indicates breakagewithin 2,000 holes, and an X indicates breakage within 30 holes.

[0094] (g) Peel Strength of Inner Layer:

[0095] Peel strength of the inner layer (kN/m) was measured as theadhesion between the inner layer copper and prepreg layer using afour-layer wiring board.

[0096] (h) Solder Heat Resistance

[0097] The test piece (50 mm×50 mm, half coated with copper on onesurface) following holding for 6 hours in a pressure cooker treatmentapparatus at 121° C. and 2130 hPa was immersed in a solder bath heatedto 260° C. for 30 seconds followed by observation of the occurrence ofblistering (h1) and measling (h2) with naked eyes. In the table, thesymbol ∘ indicates no change, Δ indicates the occurrence of measling orlifting, and X indicates the occurrence of blistering.

[0098] (i) Glass transition temperature (Tg)

[0099] Tg was measured according to the TMA method defined inJIS-C-6481. Incidentally, the sample was heated to equal to or above theglass transition temperature at a heating rate of 10° C./min, and aftertemporarily cooling to room temperature, the sample was again heated atthe heating rate of 10° C./min followed by measurement of the amount ofdimensional change, after which the glass transition temperature (° C)was determined from a “Temperature vs. Dimensions” curve. TABLE 1Formulation of Composition (1) (parts by weight) Exam- Exam- Exam- Exam-Exam- Exam- Exam- ple 1 ple 2 ple 3 ple 4 ple 5 ple 6 ple 7 A1 43 43 430 0 0 0 A2 0 0 0 43 43 0 0 A3 0 0 0 0 0 68 0 A4 0 0 0 0 0 0 68 B1 0 0 00 0 16 16 B2 21 21 21 21 21 0 0 C1 36 36 36 36 36 16 16 C2 0 0 0 0 0 0 0C3 0 0 0 0 0 0 0 D 63 63 63 63 63 82 82 E 17 17 17 17 0 12 12 F 4 4 0 00 4 4 G 4 0 0 0 0 0 0

[0100] TABLE 2 Formulation of Composition (2) (parts by weight) Exam-Exam- Exam- Exam- Exam- Exam- Exam- ple 8 ple 9 ple 10 ple 11 ple 12 ple13 ple 14 A1 43 43 43 0 0 0 0 A2 0 0 0 43 43 0 0 A3 0 0 0 0 0 41 41 A4 00 0 0 0 0 0 B1 0 0 0 0 0 0 0 B2 21 21 21 21 21 18 18 C1 36 36 36 36 3625.5 25.5 C2 0 0 0 0 0 15.5 15.5 C3 0 0 0 0 0 0 0 D 63 63 63 260 0 62 62E 17 17 27 0 0 17 17 F 4 12 0 0 0 4 0 G 12 0 0 0 0 0 0

[0101] TABLE 3 Formulation of Composition (3) (parts by weight) Exam-Exam- Exam- Exam- Exam- Exam- Exam- ple 15 ple 16 ple 17 ple 18 ple 19ple 20 ple 21 A1 0 0 0 0 0 0 0 A2 0 0 0 0 0 0 0 A3 0 41 68 41 68 41 41A4 41 0 0 0 0 0 0 B1 0 0 16 0 0 0 0 B2 18 18 0 18 16 18 18 C1 25.5 36 325.5 3 39 16 C2 15.5 5 13 0 0 2 25 C3 0 0 0 15.5 13 0 0 D 62 82 82 62 8262 62 E 17 17 12 17 12 17 17 F 0 4 4 4 4 4 4 G 0 0 0 0 0 0 0

[0102] TABLE 4 Formulation of Composition (4) (parts by weight)Comparative Comparative Comparative Comparative Comparative Comparativeexample 1 example 2 example 3 example 4 example 5 example 6 A1 0 0 0 0 00 A2 23 47 78 0 0 0 A3 0 0 0 23 36 78 A4 0 0 0 0 0 0 B1 16 15 16 16 1616 B2 0 0 0 0 0 0 C1 61 48 6 48 35 1 C2 0 0 0 13 13 5 C3 0 0 0 0 0 0 D82 82 82 82 82 82 E 12 12 12 12 12 12 F 4 4 4 4 4 4 G 0 0 0 0 0 0

[0103] TABLE 5 Characteristics evaluation (1) Characteristics Example 1Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 Dielectric0.011 0.01 0.01 0.01 0.01 0.01 0.01 tangent (1 GHZ) Bending 31 31 31 3131 32 32 elasticity Amount of warping 0.3 0.3 0.3 0.3 0.3 0.2 0.2 ofsix-layer board Flame retardancy V-0 V-0 V-0 V-0 V-0 V-0 V-0 (1.6 mm)Flame retardancy V-0 V-0 V-0 V-0 V-0 V-0 V-0 (0.8 mm) Amount of peeling0.7 1 1.2 1.5 1.3 1.5 3 during punching Drill breakage ⊚ ⊚ ⊚ ◯ ◯ ◯ ◯Inner layer 0.75 0.55 0.55 0.5 0.6 0.5 0.4 peeling strength Solder heat◯ ◯ ◯ ◯ ◯ ◯ ◯ resistance (blister) Solder heat ◯ ◯ ◯ ◯ ◯ ◯ ◯ resistance(Measling) Tg (° C.) 145 147 148 148 152 148 148

[0104] TABLE 6 Characteristics evaluation (2) Characteristics Example 8Example 9 Example 10 Example 11 Example 12 Example 13 Example 14Dielectric 0.014 0.013 0.011 0.008 0.014 0.0070 0.0071 tangent (1 GHz)Bending 28 27 27 34 28 27 28 elasticity Amount of warping 0.4 0.5 0.40.5 0.4 0.5 0.4 of six-layer board Flame retardancy V-0 V-0 V-0 V-0 V-0V-0 V-0 (1.6 mm) Flame retardancy burning burning V-0 V-0 V-1 V-0 V-0(0.8 mm) Amount of peeling 0.6 0.9 1.3 3.2 0.9 0.8 1.0 during punchingDrill breakage ⊚ ⊚ ⊚ ◯ ⊚ ⊚ ⊚ Inner layer 0.72 0.53 0.51 0.22 0.52 0.750.55 peeling strength Solder heat ◯ ◯ ◯ X ◯ ◯ ◯ resistance (blister)Solder heat X X X X ◯ ◯ ◯ resistance (Measling) Tg (° C.) 110 115 105155 155 142 147

[0105] TABLE 7 Characteristics evaluation (3) Characteristics Example 15Example 16 Example 17 Example 18 Example 19 Example 20 Example 21Dielectric 0.0070 0.0070 0.0060 0.0070 0.0060 0.0070 0.0071 tangent (1GHZ) Bending 28 29 31 27 31 28 26.5 elasticity Amount of warping 0.4 0.30.3 0.5 0.3 0.4 1.0 of six-layer board Flame retardancy V-0 V-0 V-0 V-0V-0 V-0 V-0 (1.6 mm) Flame retardancy V-0 V-0 V-0 V-0 V-0 V-0 V-0 (0.8mm) Amount of 1.3 1.0 1.0 1.2 1.5 1.4 0.7 peeling during punching Drillbreakage ⊚ Δ X ⊚ Δ ⊚ ⊚ Inner layer peeling 0.50 0.70 0.50 0.60 0.50 0.550.78 strength Solder heat ◯ ◯ ◯ ◯ ◯ ◯ ◯ resistance (blister) Solder heat◯ ◯ ◯ ◯ ◯ ◯ ◯ resistance (Measling) Tg (° C.) 148 144 144 144 148 144118

[0106] TABLE 8 Characteristics evaluation (4) Comparative ComparativeComparative Comparative Comparative Comparative Characteristics example1 example 2 example 3 example 4 example 5 example 6 Dielectric 0.0220.019 0.008 0.0120 0.0110 0.0060 tangent (1 GHZ) Bending 25 26 34 24 2534 elasticity Amount of 1.5 1.2 0.2 1.7 1.5 0.2 warping of six- layerboard Flame retardancy V-1 V-0 V-0 V-1 V-0 V-0 (1.6 mm) Flame retardancyV-1 V-1 V-0 V-1 V-1 V-0 (0.8 mm) Amount of peeling 1 1.2 3 0.7 1.0 2.8during punching Drill breakage ⊚ ⊚ ◯ ⊚ ⊚ ⊚ Inner layer peeling 0.65 0.60.1 0.75 0.65 0.10 strength Solder heat ◯ ◯ ◯ ◯ ◯ ◯ resistance (blister)Solder heat X ◯ ◯ ◯ ◯ ◯ resistance (Measling) Tg (°C.) 118 122 155 115119 148

[0107] On the basis of the above results, it was able to be confirmedthat the present invention is able to achieve low dielectric dissipationfactor and high modulus of elasticity, little warping during a built-upcomposition, high heat resistance and high Tg, while at the same timebeing able to inhibit inner layer peeling that occurs during blank dieprocessing, achieve superior small diameter drill breakage, and a levelof flame retardancy of V-0 in the standard UL94 at a content of halogenand antimony compound being 0.25% by weight or less. In addition, thehalogen content was 0.02% by weight or less with a bromine ion, and0.01% by weight or less with a chlorine ion.

[0108] Utilizability in Industry

[0109] According to the present invention, a thermosetting resincomposition having superior balance between characteristics such as lowdielectric dissipation factor, high modulus of elasticity, high heatresistance, low moisture absorption, high Tg and flame retardancy, andprocessability, along with a prepreg, laminated board for a wiringboard, printed wiring board, molding material and adhesive compositionin which it is used, are able to be obtained.

[0110] Moreover, by adding inorganic filler or condensed phosphate esteras additives having the effect of enhancing flame retardancy to thecomposition of the present invention, it becomes possible to obtainsynergistic effects as compared with the case of using each flameretardant alone due to the combined use of these flame retardants havingdifferent flame retarding action and working temperature ranges, therebymaking it possible to obtain a thermosetting resin composition havingsuperior balance among stability, flame retardancy and othercharacteristics.

[0111] In addition, according to the present invention, a laminatedboard for a printed wiring board and a printed wiring board material canbe obtained which, simultaneous to having little warping, high heatresistance and high Tg during a built-up composition with low dielectricdissipation factor and high modulus of elasticity, has superior blankdie processability and drilling, peel strength of the inner layer, whichindicates adhesive strength with the resin layer in contact with theinner layer circuit of a multi-layer wiring board, is improved, thecontent of halogen and antimony compounds is 0.25% by weight or less,and a level of flame retardancy of V-0 in standard UL94 can be achieved.

1. A thermosetting resin composition which comprises: (A) 35 to 75 partsby weight of a thermosetting resin comprising a compound having adihydrobenzoxazine ring as a main component; (B) 10 to 25 parts byweight of a polycondensation product of a phenol, a compound having atriazine ring and an aldehyde; and (C) 10 to 45 parts by weight of anepoxy resin, based on 100 parts by weight of a total amount of organicsolid components of Components (A), (B) and (C); and (i) a bisphenol Fepoxy resin having a weight average molecular weight of 1,000 to 3,000,or (ii) a mixed epoxy resin of bisphenol F epoxy resin and bisphenol Aepoxy resin having a weight average molecular weight of 1,000 to 3,000,is contained in Component (C) in an amount of 0 to 100% by weight ofComponent (C).
 2. The composition according to claim 1, wherein thecomposition further contains 5 to 300 parts by weight of (D) aninorganic filler based on 100 parts by weight of the total amount of theorganic solid components of Components (A), (B) and (C).
 3. Thecomposition according to claim 1 or 2, wherein the composition furthercontains 5 to 35 parts by weight-of (E) condensed phosphate ester basedon 100 parts by weight of the total amount of the organic solidcomponents of Components (A), (B) and (C).
 4. The composition accordingto any one of claims 1 to 3, wherein Component (A) has a softening pointof 110° C. or lower.
 5. The composition according to any one of claims 1to 4, wherein the composition further contains 1 to 20 parts by weightof (F) epoxidized polybutadiene based on 100 parts by weight of thetotal amount of the organic solid components of Components (A), (B) and(C).
 6. The composition according to any one of claims 1 to 5, whereinthe composition further contains (G) a copolymer component which is acrosslinking copolymer having a crosslinked structure and a granularform having a mean particle diameter of 2 μm or less that is selectedfrom at least one of the group consisting of acrylonitrile, acrylicacid, ethyl acrylate, butyl acrylate, glycidyl acrylate, butadiene,alkyl methacrylate and styrene, in an amount of 1 to 10 parts by weightof Component (G) based on 100 parts by weight of the total amount of theorganic solid components of Components (A), (B) and (C).
 7. Thecomposition according to any one of claims 1 to 6, wherein the contentof each halogen element in the composition is 0.25% by weight or less.8. A prepreg using the composition according to any one of claims 1 to7.
 9. The prepreg according to claim 8, wherein a prepreg base materialis a woven fabric or non-woven fabric.
 10. A laminated board for aprinted wiring board obtained by laminating metal foil on one surface orboth surfaces of the prepreg according to claim 8 or 9 followed by hotpress forming.
 11. A printed wiring board using the laminated board fora wiring board according to claim
 10. 12. A printed wiring board usingdifferent types or similar types of the prepreg according to claim 8 or9, and the laminated board for a printed wiring board according to claim10 or the printed wiring board according to claim 11.